New (virtual) Physics in the Era of the LHC

A simple extension of the Standard Model demonstrates that New Physics non-reachable through direct production at LHC can induce up to 10% corrections to the length of the unitarity triangle side, extracted from $\Delta m_{B_d}$.Comment: 5 page

Diminishing "charginos nearly degenerate with the lightest neutralino" slit using precision data

Though LEP II direct searches still cannot exclude a chargino nearly degenerate with the lightest neutralino if their mass is only slightly above half of the Z boson mass, it can be excluded indirectly analyzing precision data. In this particular limit simple analytical formulas for oblique electroweak radiative corrections are presented.Comment: 6 pages, latex, 2 figures included; published on PLB. Bounds on chargino mass are improved; two references are adde

On the production of a lepton pair in the collision of ultrarelativistic neutral particle with nonzero magnetic moment with nuclei

Explicit formulas which describe muon pair production in reaction $\gamma\nu \to \mu^+ \mu^- \nu$ through neutrino magnetic moment are obtained and used to derive in the leading approximation cross section of muon pair production in $\nu N$-scattering due to neutrino magnetic moment. This cross section appears to be proportional to $\log^4 E_{\nu}$. Comparison with experimental data on tridents production provides an upper bound $\mu_{\nu_{\mu}} < 4*10^{-8} \mu_B$, which is approximately two orders of magnitude weaker than that from $\nu_{\mu}e$ elastic scattering data.Comment: 9 pages, 4 figures, numerical estimates are improve

Stimulated Neutrino Conversion and Bounds on Neutrino Magnetic Moments

Recent experiment proposed to observe induced radiative neutrino transitions are confronted to existing bounds on neutrino magnetic moments from earth-based experiments. These are found to exclude any observation by several orders of magnitude, unless the magnetic moments are assumed to be strongly momentum dependent. This possibility is discussed in some generality, and we find that nontrivial dependence of the neutrino form factor may indeed occur, leading to quite unexpected effects, although this is insufficient by orders of magnitude to justify the experiments.Comment: one reference modified + minor changes, 8 pages, plain Late

First evidence for electroweak radiative corrections from the new precision data

The analysis of the newest data on the leptonic Z-decays and m.sub(W) appears to reveal the first manifestations of electroweak radiative corrections. In fact, these data differ, at the level of 2.sigma., from their electroweak Born values, while they agree, to within 1.sigma., with the theoretical values which take the electroweak radiative corrections into account. Previous data were within 1.sigma. in agreement with both sets of values.The analysis of the newest data on the leptonic $Z$-decays and $m_W$ appears to reveal the first manifestations of electroweak radiative corrections. In fact, these data differ, at the level of $2\sigma$, from their electroweak Born values, while they agree, to within $1\sigma$, with the theoretical values which take the electroweak radiative corrections into account. Previous data were within $1\sigma$ in agreement with both sets of values

Extra quark-lepton generations and precision measurements

The existence of extra chiral generations with all fermions heavier than M_Z is strongly disfavoured by the precision electroweak data. However the data are fitted nicely even by a few extra generations, if one allows neutral leptons to have masses close to 50 GeV. The data allow inclusion of one additional generation of heavy fermions in SUSY extension of Standard Model if chargino and neutralino have masses close to 60 GeV with \Delta m =~ 1 GeV.Comment: 14 pages, 5 figure

Extra generations and discrepancies of electroweak precision data

It is shown that additional chiral generations are not excluded by the latest electroweak precision data if one assumes that there is no mixing with the known three generations. In the case of ``heavy extra generations'', when all four new particles are heavier than $Z$ boson, quality of the fit for the one new generation is as good as for zero new generations (Standard Model). In the case of neutral leptons with masses around 50 GeV (``partially heavy extra generations'') the minimum of $\chi^2$ is between one and two extra generations.Comment: 10 pages, TeX. An additional reference and P.P.S. about heavy higgs are adde

Difference of \tilde \epsilon and \epsilon in fitting the parameters of CKM matrix

The difference between induced by box diagram value of \tilde \epsilon and experimentally measured value of \epsilon is estimated. It appeared to be around 5 - 10 %, depending on the values of hadronic matrix elements. With this result, the fit of CKM marix parameters within the SM is performed.Comment: 11 pages, 1 figur

QCD Corrections to Electroweak Annihilation Decays of Superheavy Quarkonia

QCD corrections to all the allowed decays of superheavy groundstate quarkonia into electroweak gauge and Higgs bosons are presented. For quick estimates, approximations that reproduce the exact results within less than at worst two percent are also given.Comment: 20 pages RevTeX, 9 figures. The complete paper, including figures, is also available via anonymous ftp at (129.13.102.139) as ftp://ttpux2.physik.uni-karlsruhe.de/ttp95-05/ttp95-05.ps, or via www at http://ttpux2.physik.uni-karlsruhe.de/cgi-bin/preprints

Higgs potential bounds on extra quark-lepton generations

We consider the bounds for the values of higgs mass $M_H$ and of the mass of the extra quarks and leptons $M_{extra}$ derived from the stability of vacuum and from the absence of Landau pole in Higgs potential. We find that in the case of the absence of new physics up to the GUT scale the bounds for the mass of the 4th generation are so restrictive that the negative result of CDF search for extra quarks closes the window for fourth generation. In the case of the absence of new physics up to $10^5$ GeV we get weaker but still nontrivial bounds on $M_H$ and $M_{extra}$ as well.Comment: 7pp, LaTeX, uses epsf, 5 figures, PS file available at http://venus.itep.ru/preprints/1995/95058.ps.g